A double from Tommy Bowe and a further try from Rory Best was enough to give Ireland a 22-10 win over the USA Eagles in their opening clash of the World Cup.

Ireland's winning margin suffered from the poor kicking of Jonathan Sexton, who missed two of his six shots at goal and looked unconvincing until his 50th minute substitution for Ronan O'Gara. A late intercept try from Paul Emerick also ate into Ireland's lead, though the USA deserved reward for the resolve they displayed.

Declan Kidney's men will be pleased to have avoided the nerve-jangling start to the World Cup endured by fellow home nations England and Scotland, but there is plenty to work on before they face Australia on Saturday. The failure to secure bonus points - their third try was delivered by Bowe in the 60th minute - will frustrate and they were far from convincing throughout.

Though positioned 10 places lower in the International Rugby Board world rankings at 18th, Eddie O'Sullivan's USA had the potential to present a challenging start to Pool C. Eight hours before kick off they attended a memorial service at St Andrew's church in New Plymouth to mark the 10th anniversary of September 11.

Charged by the occasion and assisted by wet and blustery conditions that made it difficult for Ireland to capitalise on their superior skills, they performed admirably until the final whistle. O'Sullivan will glean satisfaction from troubling his former paymasters and his side never looked like being overwhelmed.

Ireland were dangerous in flashes, including the start when Keith Earls sped through a half-gap only for the supporting Jamie Heaslip to run the wrong line. It took a try-saving tackle on Brian O'Driscoll by wing Takudzwa Ngwenya to keep Ireland out in the eighth minute, but Sexton's problems continued when he missed a second penalty.

A smart run from Conor Murray troubled the Eagles and when the underdogs infringed at the breakdown, Sexton was on hand to nudge Ireland into the lead. Winger James Paterson was well wide with a penalty but the USA refused to be dispirited as they renewed their attack on the Irish 22. Ireland were guilty of trying to play too much rugby and at times their tempo was a little frantic. The scrum was proving a happy hunting ground and the USA were shunted backwards once more, allowing Sexton to dash clear of the first line of defence.

Ireland began pounding at the whitewash and their reward came in the 40th minute when Bowe took an inside pass from Sexton and sped over with Sexton converting.

The Eagles approached every scrum with dread and their pack buckled under pressure once more, though this time they went unpunished as Sexton's accuracy failed him. A further three points went begging as nerves began to overcome the misfiring Sexton and his miserable afternoon concluded when he was replaced by O'Gara with Eoin Reddan coming on for Murray.

The USA produced a rousing defensive effort to repel an Irish attack led by Stephen Ferris. Paterson was on target from in front of the posts as the Irish infringed, but the fightback was brief.

Using a line-out catch and drive to set up a strong position, Best peeled from the back of the drive, stepped inside a group of cover tacklers and dived over. O'Gara fared little better than Sexton on the conversion, directing his attempt well wide, but he was on target after Ireland ran in their third try.

Slick hands sent Bowe sliding over after the Osprey had come off his wing to exchange passes with Brian O'Driscoll. Errors began to creep into Ireland's game, though this was partly due to the Eagles' robust defence.

Their opponents tiring, Ireland began to tighten the screw up front but fought in vain to breach the whitewash for the try-scoring bonus point. Instead it was the USA who had the final say when centre Paul Emerick rain in a late intercept try.